Physical vapor deposition is commonly used within the semiconductor industry, as well as within solar, glass coating, and other industries, in order to deposit a layer over a substrate. Sputtering is a common physical vapor deposition method, where atoms or molecules are ejected from a target material by high-energy particle bombardment and then deposited onto the substrate.
In order to identify different materials, evaluate different unit process conditions or parameters, or evaluate different sequencing and integration of processes, and combinations thereof, it may be desirable to be able to process different regions of the substrate differently. This capability, hereinafter called “combinatorial processing”, is generally not available with tools that are designed specifically for conventional full substrate processing. Furthermore, it may be desirable to subject localized regions of the substrate to different processing conditions (e.g., localized deposition) in one step of a sequence followed by subjecting the full substrate to a similar processing condition (e.g., full substrate deposition) in another step.
Current full-substrate PVD tools used in semiconductor industry utilize a large sputter gun and large target, i.e., the target is larger than a wafer for uniform film deposition on the wafer, even for wafers as large as 300 mm. Alternatively, some full wafer PVD tools use a smaller sputter gun, e.g., 3″ or 4″ diameter, with a rotating wafer, where the wafer may be 200 mm diameter or smaller and the sputter gun is pointed to the mid-radius of the wafer and the target-to-wafer spacing is relatively large, e.g., 200 mm. Combinatorial processing chambers typically include smaller sputter guns. In order to achieve high metal ionization to improve step coverage a relatively high power, e.g., greater than 10 kilowatts, may be needed to be applied to the sputter gun and the substrate is biased. However, this high power lasting a relatively long period of time can damage the sputter gun, especially the smaller diameter guns.
What is needed is the ability to achieve high metal ionization without damaging the sputter guns, especially the smaller diameter sputter guns. It is within this context that the current embodiments arise.